Cobalt siccatives



Patented Oct. 10, 1944 STATES comm srooa'rrvas John T. Rutherford, Berkeley, Calii'., assignor to Standard Oil Company or California, San Francisco, Calii.. a corporation of Delaware No Drawing. Application August 27, 1938, Serial No. 227,178

i'jlaims. (Cl. 260-439) nishes, ink oils and the like as a drying agent.

Prior to its incorporation in paints, varnishes and the like, cobalt naphthenate is often dispensed and stored as an essentially pure dry solid, sometimes in massive and sometimes in finely pulverized form. Upon storage, and particularly upon exposure to air, cobalt naphthenate deteriorates to such an extent that considerable proportions become insoluble in oil, whether by the formation of oxides or of oilinsoluble salts is not exactly understood. This degradation of cobalt naphthenate, which in its normal state is completely oil-soluble, is manitested by a progressive change in color, from an original deep blue-purple to a green and finally to a brown. As these color changes take place, the naphthenate becomes progressively less soluble in petroleum thinners and drying oils, rendering it useless as a paint drier; for example, a finely pulverized cobalt naphthenate may become entirely insoluble in oil and thinners upon the lapse of some months, when exposed to the air.

Likewise prior to its incorporation in paints,

or less extent, which deterioration is likewise by the preponderant amounts of vehicles, pig' ment, etc. with which it is then associated. It will accordingly be understood that the effects described, and the invention here disclosed, are concerned entirely with the drier itself, in solid or in dissolved or so-called liquid form, before incorporation in the preponderant amounts 01' vehicles and pigments which together constitute an ultimate paint, varnish, ink oil or the like type of composition.

It has now been found that the intimate admixture of a very small amount of certain in-' hibiting agents will remarkably postpone the above deterioration or degradation, that in the presence of such agents the cobalt naphthenate retains its original complete solubility in thinness and oils, and that the color changes which normally accompany the usual progressive deterioration do not manifest themselves with their normal rapidity. In general, the agents found to stabilize cobalt naphthenate against the untoward degrading effects here noticed are P the aromatic hydroxy compounds, and derivatives of aromatic-hydroxy compounds, as more fully exemplified herein below.

It is a purpose of this invention to disclose and provide cobalt naphthenate compositions, as solids and as solutions in oils and thinners, which do not deteriorate to form oil-insoluble substances at the normal rates at which such deterioration occurs, and to disclose and provide methods by which such stabilization may be accomplished. It is a further object of this invention to disclose and provide cobalt naphthenate. compositions, in dissolved as well as in 'undissolved form, which contain aromatic-hydroxy compounds in suflicient amount and in sufficient intimacy of association to effect these stabilizations against colorand solubility-alterations. I

In exemplification of the methods and compositions of the invention:

Inasmuch as the initiation and progress of oil-insolubility of cobalt naphthenate have been found to be manifested through accompanying changes in color, it has been found convenient to measure the effectiveness of the inhibiting agents by the observation of such color changes, for example in the following manner: Ordinary analytical filter paper is dipped in a solution of the cobalt naphthenate in a volatile mineral thinner, or some drops of such a solution are allowed to fall upon such a porous paper. The thinner rapidly evaporates, leaving a residue of very finely divided solid cobalt naphthenate of extensive surface area. The paper is exposed to the air and is observed periodically for such color changes as may appear in the solid cobalt naphthenate particles, such color changes taking the following course: purple (original), greenish traces, green, dark green, brown (ultimate). Ordinarily the progress toward dark green is suflicient to ascertain the efiectiveness of the Number of days before first appearance o1' Greenish Dark traces Green green Cobalt naphthenate alone 5 7 11 +1.0 pyrogallol 20 20 20 +0.1 240-300 C. wood tar distillate cresols 20 20 20 +10% ISO-205 0. cracked petroleum naphtha cresols l3 13 20 Generally, from 0.05% to 2.0% by weight of the aromatic-hydroxy compounds, based on the cobait naphthenate and intimately admixed with itin either solid or dissolved form, will be found sufficient for the purposes of the invention. Amounts of these compounds as high as by weight will in most cases cause only an inconsiderable improvement over th employment of 2.0% by weight.

The mono-, di-, triand poly-phenols and their alkyl derivatives, such as the methyl, ethyl, propyi, isopropyl, butyl, isobutyi and higher homologues, the cresols. hydroquinone, phloroglucinol, pyrocatechol, pyrogalloi, resorcinol and the naphthols, especially beta-naphthol, as well as the acyl derivatives thereof, such as the acetyl,

propionyl, butyryl, valeryl and higher homologues thereof, may be employed in the practice of the invention.

In preparing the compositions of the invention, intimate admixture of the stabilizing agent with the cobalt naphthenate is essential. This may be accomplished by dissolving the requisite amount of the agent in a solvent and dispersing it on the surface of the solid particles of cobalt naphthenate; the evaporation of the solvent leaves a residual quantity of the agent in sufliciently widely dispersed form. In the event that th cobalt naphthenate is manufactured in liquid form, that is, in solution in a thinner or solvent, the agent may merely be incorporated in the solvent itself; or the inhibitory substance may be added during the course of the formation of the metal naphthenate salt itself, so long as the progress of the formation allows it to accompany the naphthenate and remain permanently and intimately associated therewith. The principal desideratum here is that the aromatic hydroxy compound may be allowed to function in the manner intended for the practice of the invention, namely, in sufficient amount and in sufficiently intimate association with the cobalt naphthenate to enable it to inhibit or entirely prevent the deteriorations in oil-solubility and color referred to herein above.

Certain obvious modifications of the invention as above described will be apparent to one skilled in the art, and it will be understood that while the character of the invention and numerous illustrative examples of its practice have been described in detail, this has been done by way of illustration only and with the intention that no limitation be imposed upon the invention, which includes all such changes and modifications as come within the scope of the appended claims,

I claim:

1. A cobalt naphthenate siccative stabilized against color change and decrease in oil solubility comprising cobalt naphthenate and an inhibiting agent comprising a cresol, said cobalt naphthenate without said inhibiting agent being subject to color change and decrease in oil solubility, and said inhibiting agent being mixed with said cobalt naphthenate in a proportion suflicient to inhibit color change and decrease in oil solubility of said cobalt naphthenate.

2. A cobalt naphthenate slccative stabilized against color change and decrease in oil solubility comprising cobalt naphthenate and an inhibiting agent comprising -205 C. cracked petroleum naphtha cresols, said cobalt naphthenate without said inhibiting agent being sub ject to color change and decrease in oil solubility, and said inhibiting agent being intimately mixed with said cobalt naphthenate in a proportion sufficient to inhibit color change and decrease in oil solubility thereof.

3. A cobalt naphthenate siccative stabilized against color change and decrease in oil solubility comprising cobalt naphthenate and between 0.05% and 5.0% of its weight of a cresol.

4. A cobalt naphthenate siccative stabilized against color change and decrease in oil .solubility comprising cobalt naphthenate and between 0.05% and 5.0% of its weight of cracked petroleum naphtha cresols.

5. A cobalt naphthenate siccative stabilized against color change and decrease in oil solubility comprising cobalt naphthenate and between 0.05% and 5.0% of its weight of a 180-205 C. fraction from cracked petroleum naphtha cresols.

JOHN T. RUTHERFORD. 

